The 6-deoxy sugars constitute particularly useful starting materials for the preparation of 4-hydroxy-2,5-dimethyl-2,3-dihydrofuran-3-one, better known by the name of FURANEOL.RTM. (registered trademark of Firmenich SA, Geneva). M. Matsui et al. [see Chem. Abstr., 91, 20309q (1979)], for example, have described the method for converting 6-deoxy-D-glucose into FURANEOL. Although the yields observed during this conversion were very satisfactory, the method of Matsui suffers from a major drawback, i.e., the high cost of the starting material whose preparation requires four reaction steps. This invention concerns an original solution to this problem. We have found that 6-deoxy-D-fructose and 6-deoxy-L-sorbose, of the following formulas respectively ##STR1## can be converted into FURANEOL in excellent yield, with the conversion taking place in the presence of an organic nitrogen base and a carboxylic acid, under reaction conditions similar to those described by Matsui.